Chapter 5 Loops

Question 1

The do while loop definition

Answer 1

A do-while loop is the same as a while loop except that it executes the loop body first then checks the loop continuation condition.

This means that a do-while loop will always be executed at least once.

Question 2

The do while loop syntax

Answer 2

do {
<statement(s)>
<update>
} while (<condition>);</condition></update>

Question 3

Taking user input for do while loops

Answer 3

Scannerinput=newScanner(System.in);
intdata;
intsum=0;

do{
System.out.println(“Enteraninteger(enter0tostop)”);
data=input.nextInt();
sum+=data;
}while(data!=0);
System.out.println(“Thesumis”+sum);

Question 4

How do you end do-while loop

Answer 4

The following while loop is wrong:
int i=0;
while (i < 10);
{
System.out.println(“i is “ + i);
i++;
}

In the case of the do-while loop, the following semicolon is needed to end the loop.
int i=0;
do {
System.out.println(“i is “ + i);
i++;
} while (i<10);

Question 5

What does a for loop consist of

Answer 5

1) initialization section - is executed once at the start of the loop
2) continuation section - is evaluated before every loop iteration to check for loop termination
3) next iteration section - is evaluated after every loop iteration to update the loop counter

Question 6

for loop syntax

Answer 6

for (<initialization>; <condition>; <update>) { <statement(s)>
}</update></condition></initialization>

Question 7

Write a for loop that prints “Welcome to Java” 100 times

Answer 7

int i;
for (i = 0; i < 100; i++) {
System.out.println(“Welcome to Java!”);
}

Question 8

An infinite loop is caused when?

Answer 8

loops conditions are incorrect.

for (int i = 0; i < 10; i–){ // Should have been i++
System.out.print(i + “, ”); // Infinite loop: 0, -1, -2, ..
}

int j = 0;
while (j < 10){
System.out.print(j + “, ”); // Infinite loop: 0,0,0,..
} // Forgot to change j in loop

Question 9

How do you purposely create an infinite loop

Answer 9

To purposely create an infinite while loop, use the Boolean literal true as the condition.
If the condition in a for loop is omitted, it is implicitly true and will cause an infinite loop.

Question 10

Nested loops definition

Answer 10

A loop can be nested inside another loop.

Nested loops consist of an outer loop and one or more inner loops. Each time the outer loop is
repeated, the inner loops are reentered, and started anew.

Question 11

Note: 1 microsecond is ____ of a second

Answer 11

one-millionth (10^(−6))

Question 12

When do you use a break statement

Answer 12

You have used the keyword break in a switch statement. You can also use break in a loop to immediately terminate the loop.

Question 13

When do you use a continue statement

Answer 13

You can also use the continue keyword in a loop. When it is encountered, it ends the current iteration and program control goes to the end of the loop body.